This invention pertains to a rectangular or polygonal lab having slots in one of its faces communicating with a plurality of longitudinal passages in the body of the slab. The slab is designed for use as a module in the two-stage construction of a poured concrete deck or plate. The rectangular or polygonal slab module is in the form of a slotted floor slab which serves as the lower form for the complete concrete deck or plate, and at the same time contains the bending reinforcement for the whole plate. The slab constitutes the first stage in the construction of the deck or plate. In constructing the concrete deck a plurality of slotted floor slab modules is engaged to the concrete deck or plate, when the concrete slurry to create the deck enters the longitudinal passages in the slotted floor slab through the slots in the face of the slab. The intimate connection between the slotted floor slab and the concrete deck created by the adherence of the concrete in the longitudinal walls of the passages in the upper face thereof allows both layers, that of the slotted floor slab, and that of the poured deck, to behave in an integral manner, constituting a completed full level deck or plate.
The fundamental characteristic which distinguishes the slotted floor slab from conventional two-stage floor plates lies in the process through which shearing or shearing stress is transmitted between the slotted floor slab and the upper deck of poured concrete, poured over such slotted slab, to conform the final floor plate. The slots in the upper face of the slotted floor slab allow the concrete of the upper deck to enter the longitudinal passages in the body of the slab and to become embedded inside the slotted floor slab, forming an intimate contact between the two elements, joined precisely to the cores and the lower reinforcement of the slotted floor slab, which in turn provides the main reinforcement of the deck or plate, thus achieving an excellent transmission of the diagonal shearing stress between the lower traction reinforcing and the compression zone in the upper deck.
Another very important distinguishing characteristic is the mechanism through which the slotted floor slab accommodates loads generated by construction and by the poured upper deck itself, because its elements for receiving compression stress, upper reinforcement and the upper surface of the element, are placed inside the rectangular parallelopiped of the part, rather than having protruding trusses on the upper face of the element, outside of its regular prismatic shape, as is true for the existing shuttering floor slabs. This is possible because the floor slab is considerably thick, while at the same time it is light in weight owing to the weight-reducing effect of the hollow parallel passages provided along the longitudinal axis of the element. The thickness is sufficiently significant so that a sheet of the slotted floor slabs offers a resisting moment which is capable of withstanding loads generated by handling and construction, aided only by a temporary form in the center of the span, if the span which is covered exceeds 25 times the thickness of the slotted floor slab.
Another considerable difference .in the slotted floor slab is that it requires less concrete in the poured upper layer. This results in savings in terms of the weight of the full deck, and savings in terms of materials in the poured upper layer. This is achieved by the thickness of the slotted floor slab, by virtue of which the concrete in the upper deck is generally totally within the compression zone of the full deck, because the required thickness of the poured upper deck is smaller than that of the slotted floor slab. While in conventional two-stage construction of floor slabs, the concrete in the upper layer remains well on both sides of the neutral axis of the final slab and thus the structural contribution of the mass under the plane of the neutral axis is nil, only serving negatively to increase the dead or static load of the full plate.